Floating contact means

ABSTRACT

A circuit breaker having a pair of spaced insulated stationary contacts engageable by a pair of movable contacts mounted to a conducting bridge on a movable contact arm is provided with common means defining main and auxiliary pivot axes for the contact arm. The main axis is transverse to the arm and provides a center about which the movable contacts pivot as they separate from the stationary contacts. The auxiliary axis is parallel to the longitudinal axis of the arm and provides a center for limited pivoting of the arm to obtain automatic seating of the movable contacts on the stationary contacts.

United States Patent Zubaty et al. 1 Feb. 4, 1975 1 FLOATING CONTACT MEANS 3,194,934 7/1965 Gauthier 200/248 Inventors: Martin v. y, Benefomaine 3,663,905 5/1972 Kussy et al 335/195 Ohio; Frank W. Kussy, l-laverford; Gustave E. l-leberlein, .lr., Chalfont, Pr'mary Exammer aarold Broome Attorney, Agent, or Fzrm-Ostrolenk, Faber, Gerb & 1 both of Pa. soffen [73] Assignee: I-T-E Imperial Corporation, Spring House 57 ABSTRACT [22] Flled: 1974 A circuit breaker having a pair of spaced insulated sta- [21] Appl. No.: 447,654 tionary contacts engageable by a pair of movable contacts mounted to a conducting bridge on a movable contact arm is provided with common means de- [gill] 335/19 230/342 fining main and auxiliary pivot axes for the Contact I} 0 arm. The main a is transverse to t e arm and 58 F 1d is h 335194 192 195 200' p 1 0 care 6 vides a center about which the movable contacts pivot as they separate from the stationary contacts. The auxiliary axis is parallel to the longitudinal axis of the [56] References cued arm and provides a center for limited pivoting of the UNITED STATES PATENTS arm to obtain automatic seating of the movable 2,480,161 8/1949 Prescott 335/192 contacts on the stationary contacts. 2,740,022 3/1956 Simpson 200/248 3,153,790 11/1964 Lemonnier .1 333/200 10 Clalms, 6 Drawing Flgures PATENTEU FEB 4' FLOATING CONTACT MEANS This invention relates toelectrical switches in general and more particularly relates to means for assuring proper seating of bridging contact means to increase switch life.

The F. W. Kussy et al. U.S. Pat. No. 3,663,905, issued May 16, 1972, for a Contact Bridge System For Circuit Breaker, discloses a current limiting circuit breaker in which each pole includes a bridging contact having a pair of movable contacts engageable with a pair of spaced insulated stationary contacts. As either or both pairs of contacts wear from erosion or otherwise-at unequal rates, the problem of proper consistent contact pressure is much more acute than in circuit breakers of lower current ratings.

To assure sufficient contact pressure under all conditions of contact wear, the instant invention provides means for automatic seating of the movable contacts on the stationary contacts. This is accomplished by mounting the movable contact arm for movement about a main pivot as well as an auxiliary pivot. The main pivot is transverse to the contact arm and provides a center for movement of the contact arm to open circuit position. The auxiliary pivot extends parallel to the longitudinal axis of the contact arm and permits limited tilting of the contact arm so as to permit the movable contacts mounted thereto to seat properly on the stationary contacts.

Accordingly, a primary object of the instant invention is to provide novel means for maintaining contact pressure in a circuit breaker after erosion and other wear at the circuit breaker contacts.

Another object is to provide a relatively high current circuit breaker with a contact arm that is tiltable about its longitudinal axis so that bridging contacts at the end of the contact arm are seated properly on spaced stationary contacts.

These objects as wellas other objects of this invention will become readily apparent after reading the following description of the accompanying drawings in .which:

FIG. 1 is a perspective showing selected elements of a circuit breaker contact structure.

FIG. 2 is a side elevation looking in the direction of arrows 2-2 of FIG. 1.

FIG. 3 is a plan view looking in the direction of arrows 3 3 of FIG. 2.

FIGS. 4 and,5 are cross-sections taken through line 44 of FIG. 3, looking in the direction of arrows 44. In FIG. 4, the contact arm is shown before contact wear and in FIG. 5 the contact arm is shown as a substantial contact wear.

FIG. 6 is a view similar to FIG. 4, showing another embodiment of the instant invention.

Now referring to the figures and more particularly to FIGS. 1-5. The contact structure shown in FIG. 1 is generally of the type disclosed in U.S. Pat. No. 3,663,905 and includes insulating support 11. A pair of stationary contacts l2, 13 is seated on the upper surface of insulating member 11 in operative positions to be engaged by the respective movable contacts l4, 15 mounted at opposite free ends of the conducting modi fled U-shaped bridge 16. The web portion 17 of bridge I6 is'rigidly secured to the forward end of insulated movable contact arm 18'that is mounted between the spaced parallel sections constituting movable support 20. The rear ends of sections 20, 20 are keyed to transverse insulated tie rod 21 which, in a manner well known to the art, interconnects the contact mechanisms of a plurality of circuit breaker poles (not shown) for simultaneous operation. As seen most clearly in FIGS. 4 and 5, arm 18 is mounted to'members 20, 20 on rod 23 of circular cross-section. Rod 23 extends between members 20, 20 and through transverse bore 24 of circular cross-section. Disposed within the central portion of bore 24 is inwardly projecting band 25 of arcuate cross-section shown operatively retained by screw 46 but which may be formed integrally with arm 18.

The fit between arcuate band 25 and rod 23 is such that these elements cooperate to define main axis 26 coinciding with the longitudinal axis of rod 23, and auxiliary axis 27 (FIG. I) coinciding with the longitudinal axis of arm 18. Main axis 26 is the center about which arm 18 pivots relative to support 20 so that tension spring 28 connected to post 31 on members 20, 20 and post 32 on arm 18 is free to exert contact pressure when the switch is closed and is free to maintain movable contacts 14, I5 separated from stationary contacts l2, 13 after these contacts are blown apart by magnetic action resulting from severe fault currents. Axis 27 provides a center about which arm 18 has limited pivotal motion (indicated by arm 47) sufficient to assure automatic seating of movable contacts l4, 15 on stationary contacts l2, 13, even though erosion and other wear at these contacts does not take place evenly. It is noted that the spaced support sections 20, 20 prevent pivotal motion of arm 18 about axis 36 which is perpendicular to both axes 26 and 27. Movement of arm 18 about axis 36 may also be presented by changing the shape of bore 24 from a circular cross-section to a generally rectangular cross-section having a minor axis only slightly larger than the diameter of rod 23.

In the embodiments of FIG. 6, the main 26 and auxiliary 27 axes are defined by spherical member 41 secured to the central portion of rod 42 that extends between the sections of support 20 and through transverse bore 43 of movable contact arm 44. Bore 43 is of circular cross-section having a diameter substantially the same as the diameter of spherical support 41.

Thus, it is seen that the instant invention provides means whereby bridging contacts mounted at the end of a pivoted contact arm are automatically seated regardless of uneven contact wear due to erosion and other causes.

Although in the foregoing this invention has been described in connection with preferred embodiments, many variations and modifications will now become apparent to those skilled in the art, and it is therefore preferred that this invention be limited not by the foregoing description but only by the appended claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

l. A switch device including stationary contact means positioned generally in a first plane, movable contact means operable into and out of engagement with said stationary contact means, an elongated arm having said movable contact means mounted thereto at its forward end, means defining a main axis positioned to the rear of said movable contact means, said movable contact means being mounted for pivotal movement about said main axis as a center to disengage said stationary contact means, with said pivotal movement being generally in a second plane at right angles to said first plane, said stationary contact means including spaced first and second contacts insulated from one another when said switch device is open, said first and second contacts being positioned so that a line extending therebetween is generally parallel to said main axis, said movable contact means includes third and fourth contacts engageable with the respective first and second contacts, a rigid conducting bridge to which said third and fourth contacts are fixedly mounted, said bridge comprising a conducting path between said first and second contacts when said switch device is closed, and means defining a single auxiliary axis about which said movable contact means is pivotable to seat said movable contact means in engagement with said stationary contact means, said auxiliary axis extending generally parallel to the longitudinal axis of said arm and at right angles to said first axis generally parallel to said second plane.

2. A switch device as set forth in claim 1 in which the main and auxiliary axes intersect at a common arcuate means.

3. A switch device as set forth in claim 1 also including a movable support to which said arm is movably connected by the means defining the main and auxiliary axes.

4. A switch device as set forth in claim 3 in which the main and auxiliary axes intersect at a common arcuate means. i

5. A switch device as set forth in claim 4 in which the arcuate means is fixedly mounted to the arm.

6. A switch device as set forth in claim 4 in which the arcuate means is fixedly mounted to the movable sup-' 7 port.

the conducting bridge is disposed forward of said axes. 

1. A switch device including stationary contact means positioned generally in a first plane, movable contact means operable into and out of engagement with said stationary contact means, an elongated arm having said movable contact means mounted thereto at its forward end, means defining a main axis positioned to the rear of said movable contact means, said movable contact means being mounted for pivotal movement about said main axis as a center to disengage said stationary contact means, with said pivotal movement being generally in a second plane at right angles to said first plane, said stationary contact means including spaced first and second contacts insulated from one another when said switch device is open, said first and second contacts being positioned so that a line extending therebetween is generally parallel to said main axis, said movable contact means includes third and fourth contacts engageable with the respective first and second contacts, a rigid conducting bridge to which said third and fourth contacts are fixedly mounted, said bridge comprising a conducting path between said first and second contacts when said switch device is closed, and means defining a single auxiliary axis about which said movable contact means is pivotable to seat said movable contact means in engagement with said stationary contact means, said auxiliary axis extending generally parallel to the longitudinal axis of said arm and at right angles to said first axis generally parallel to said second plane.
 2. A switch device as set forth in claim 1 in which the main and auxiliary axes intersect at a common arcuate means.
 3. A switch device as set forth in claim 1 also including a movable support to which said arm is movably connected by the means defining the main and auxiliary axes.
 4. A switch device as set forth in claim 3 in which the main and auxiliary axes intersect at a common arcuate means.
 5. A switch device as set forth in claim 4 in which the arcuate means is fixedly mounted to the arm.
 6. A switch device as set forth in claim 4 in which the arcuate means is fixedly mounted to the movable support.
 7. A switch device as set forth in claim 6 in which the arcuate means comprises a spherical element.
 8. A switch device as set forth in claim 7 in which the conducting bridge is disposed forward of said axes.
 9. A switch device as set forth in claim 8 in which the arcuate means is at the forward end of said movable support, and means at the rear of said movable support mounting the latter for movement generally in said second plane.
 10. A switch device as set forth in claim 1 in which the conducting bridge is disposed forward of said axes. 